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  <div class="section" id="function">
<span id="command:function"></span><h1>function<a class="headerlink" href="#function" title="Permalink to this headline">¶</a></h1>
<p>Start recording a function for later invocation as a command.</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">function(</span><span class="nv">&lt;name&gt;</span><span class="w"> </span><span class="p">[</span><span class="nv">&lt;arg1&gt;</span><span class="w"> </span><span class="p">...]</span><span class="nf">)</span><span class="w"></span>
<span class="w">  </span><span class="nv">&lt;commands&gt;</span><span class="w"></span>
<span class="nf">endfunction()</span><span class="w"></span>
</pre></div>
</div>
<p>Defines a function named <code class="docutils literal notranslate"><span class="pre">&lt;name&gt;</span></code> that takes arguments named
<code class="docutils literal notranslate"><span class="pre">&lt;arg1&gt;</span></code>, …  The <code class="docutils literal notranslate"><span class="pre">&lt;commands&gt;</span></code> in the function definition
are recorded; they are not executed until the function is invoked.</p>
<p>Per legacy, the <span class="target" id="index-0-command:endfunction"></span><a class="reference internal" href="endfunction.html#command:endfunction" title="endfunction"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">endfunction()</span></code></a> command admits an optional
<code class="docutils literal notranslate"><span class="pre">&lt;name&gt;</span></code> argument. If used, it must be a verbatim repeat of the
argument of the opening <code class="docutils literal notranslate"><span class="pre">function</span></code> command.</p>
<p>A function opens a new scope: see <span class="target" id="index-0-command:set"></span><a class="reference internal" href="set.html#command:set" title="set"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">set(var</span> <span class="pre">PARENT_SCOPE)</span></code></a> for
details.</p>
<p>See the <span class="target" id="index-0-command:cmake_policy"></span><a class="reference internal" href="cmake_policy.html#command:cmake_policy" title="cmake_policy"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">cmake_policy()</span></code></a> command documentation for the behavior
of policies inside functions.</p>
<p>See the <span class="target" id="index-0-command:macro"></span><a class="reference internal" href="macro.html#command:macro" title="macro"><code class="xref cmake cmake-command docutils literal notranslate"><span class="pre">macro()</span></code></a> command documentation for differences
between CMake functions and macros.</p>
<div class="section" id="invocation">
<h2>Invocation<a class="headerlink" href="#invocation" title="Permalink to this headline">¶</a></h2>
<p>The function invocation is case-insensitive. A function defined as</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">function(</span><span class="nb">foo</span><span class="nf">)</span><span class="w"></span>
<span class="w">  </span><span class="nv">&lt;commands&gt;</span><span class="w"></span>
<span class="nf">endfunction()</span><span class="w"></span>
</pre></div>
</div>
<p>can be invoked through any of</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">foo()</span><span class="w"></span>
<span class="nf">Foo()</span><span class="w"></span>
<span class="nf">FOO()</span><span class="w"></span>
</pre></div>
</div>
<p>and so on. However, it is strongly recommended to stay with the
case chosen in the function definition. Typically functions use
all-lowercase names.</p>
</div>
<div class="section" id="arguments">
<h2>Arguments<a class="headerlink" href="#arguments" title="Permalink to this headline">¶</a></h2>
<p>When the function is invoked, the recorded <code class="docutils literal notranslate"><span class="pre">&lt;commands&gt;</span></code> are first
modified by replacing formal parameters (<code class="docutils literal notranslate"><span class="pre">${arg1}</span></code>, …) with the
arguments passed, and then invoked as normal commands.</p>
<p>In addition to referencing the formal parameters you can reference the
<code class="docutils literal notranslate"><span class="pre">ARGC</span></code> variable which will be set to the number of arguments passed
into the function as well as <code class="docutils literal notranslate"><span class="pre">ARGV0</span></code>, <code class="docutils literal notranslate"><span class="pre">ARGV1</span></code>, <code class="docutils literal notranslate"><span class="pre">ARGV2</span></code>, …  which
will have the actual values of the arguments passed in.  This facilitates
creating functions with optional arguments.</p>
<p>Furthermore, <code class="docutils literal notranslate"><span class="pre">ARGV</span></code> holds the list of all arguments given to the
function and <code class="docutils literal notranslate"><span class="pre">ARGN</span></code> holds the list of arguments past the last expected
argument.  Referencing to <code class="docutils literal notranslate"><span class="pre">ARGV#</span></code> arguments beyond <code class="docutils literal notranslate"><span class="pre">ARGC</span></code> have
undefined behavior.  Checking that <code class="docutils literal notranslate"><span class="pre">ARGC</span></code> is greater than <code class="docutils literal notranslate"><span class="pre">#</span></code> is
the only way to ensure that <code class="docutils literal notranslate"><span class="pre">ARGV#</span></code> was passed to the function as an
extra argument.</p>
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  <h3><a href="../index.html">Table of Contents</a></h3>
  <ul>
<li><a class="reference internal" href="#">function</a><ul>
<li><a class="reference internal" href="#invocation">Invocation</a></li>
<li><a class="reference internal" href="#arguments">Arguments</a></li>
</ul>
</li>
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